Never Exceed Published Data...Unless You Do

[ArrowJ]

Thanks to some conversations with Bullwolf I have a better understanding of published data and maximum loads etc. especially as related to cast bullets. Still it can be frustrating to someone with OCD to find data that seems so incompatible as to cancel each other out for the exact same bullet in two different manuals!

I am getting ready to load some 38 Special rounds for my Dad's Model 49 J Frame Smith. I have some cast 158 grain SW that I am going to load and shoot for fun, but I want to load 125 grain jacketed bullets for my Dad as slow as I can in order to reduce recoil.

I bought 125 grain Hornady FP-XTP #35730 bullets.

The data Hornady provides is as follows:
125 grain FP-XTP
Bullseye 4.5-5.3 grains @ 800-950 FPS
COL 1.450"

The Lyman 49th data is as follows:
125 gr FP-XTP
Bullseye 3.2-4.4 grains @ 568-860 FPS
COL 1.470"

So the maximum load listed by Lyman is BELOW the minimum load listed by Hornady!

Lyman used a universal receiver with a 4" barrel and Hornady used S&W Model 15 with a 4" barrel both with the same twist.

The COL is different, but given that we adjust the COL all the time for our particular gun without undue concern for pressure that would not seem to be a factor.

As I am using a Hornady bullet I will likely use that data, and I am not actually worried about blowing up my gun, but if it is frustrating for an intermediate handloader it must be infuriating for a beginner that is told to get more than one manual and to ALWAYS FOLLOW PUBLISHED DATA!

At the end of the day it basically leaves someone in my particular situation with the freedom to pick which book he wants based on his goal and feel safe in doing so which seems problematic.

You want slow moving bullets that will not stick in your barrel or blow up your gun? Use the Lyman data at 3.2 grains. Not satisfied with the pep you are getting from Lyman's max load? Just move over to Hornday's data and you can safely add almost another grain of powder.

[dverna]

Some sources list chamber pressure. Those are the ones that I would trust the most.

Rarely, there are typos and errors in data. I normally use 3-5 references when working up a load and then check for pressure signs for metallic cartridges. It is NOT possible to check shotshells for pressure signs so only use published data.

BTW, COL does affect pressure. The deeper a bullet is seated, the higher the pressure will be.

[OS OK]

It looks like the Lyman 49 considers the loads above the 4.4g. a +P load as it does list the loads up to 5.0g.@920FPS.
See the blank line below the Bullseye listing...that's the extension for the higher load data over what they determine is standard pressure.

[ArrowJ]

BTW, COL does affect pressure. The deeper a bullet is seated, the higher the pressure will be.

Definitely, I do not disregard it. But when loading 9mm for instance, there might be a variance of +/-.010 on a progressive press and I have +/-.005 on my single stage.

The Lyman data does use a longer COL, but even that is odd to me given there is a cannelure on the bullet for crimping. I would not think it would be wide enough for a .020" difference, and given setback I would think it would not stay that way for long unless you crimped deeply into the bullet.

[ArrowJ]

It looks like the Lyman 49 considers the loads above the 4.4g. a +P load as it does list the loads up to 5.0g.@920FPS.
See the blank line below the Bullseye listing...that's the extension for the higher load data over what they determine is standard pressure.

You are correct sir! There is indeed an asterisk by the 5.3 grain load in the Hornady indicating +P. I had no intention of loading hot as I am looking for the opposite, by good to know. I do not know how long I looked at that data without noticing that! It still leaves the original discrepancy, but given that information I think I will begin with the Lyman data as Hornady seems to be pushing it hotter to begin with and that is not what I want.

So I am doing exactly what I said, choosing the manual that suits my needs :)

As mentioned, always use more than one manual. I actually looked at the Lee as well which 4.0-4.5 @ 1.440" COL.

[OS OK]

You are correct sir! There is indeed an asterisk by the 5.3 grain load in the Hornady indicating +P. I had no intention of loading hot as I am looking for the opposite, by good to know. I do not know how long I looked at that data without noticing that! It still leaves the original discrepancy, but given that information I think I will begin with the Lyman data as Hornady seems to be pushing it hotter to begin with and that is not what I want.

So I am doing exactly what I said, choosing the manual that suits my needs :)

As mentioned, always use more than one manual. I actually looked at the Lee as well which 4.0-4.5 @ 1.440" COL.

That cut the original discrepancy from .9g. to .3g. which is not all that uncommon.

[44MAG#1]

I think the OP is creating a problem where there isn't one.
Am I wrong in this though process?
Hornady uses the Win SP primer and more than likely a different lot of Bullseye.
Lyman uses a CCI500 primer.
What am I missing there OP?

[ArrowJ]

That cut the original discrepancy from .9g. to .3g. which is not all that uncommon.

Well if the range of "normal" loads is 3.2-4.4 and 4.5-5.0 you still have a working range of 3.2-4.9 if you combine the data and assume everything over 4.9 is+P.
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I do not think there is a problem per se so much as too much stress given to published load data without further explanation. I guess this has all been hashed out before. I just found it frustrating that one has a max lower than the other's min even accounting for +P. I cannot see different brands of small pistol primers making 3.2 grains unsafe on the lower end although it is possible. I mean with one primer I have to start over a grain higher? I can see a different primer pushing the load over the edge into +P. Of course they are probably also taking into account accuracy.

Again, not a problem, just thought I might learn something.

[OS OK]

We get lost in the numbers trying to split hairs. Yes we do compare apples to apples but they are just different brands of apples.
I think that here in low pressure pistol ammo we should pay close attention to the primers. When you get too hot the edge gets pretty distinctive pretty quick.
I've followed threads where they were considering ringing the barrel using the lower end loads. Most, if I remember correctly don't worry about it in a revolver because we have the space between the cylinder and the barrel where it acts like a pressure safety release blowing off overpressure quickly. But, that too is a shady grey area as this space can be a tight .003" and vary up to .032" I had in a Smith No.3., big difference there.

[ArrowJ]

We get lost in the numbers trying to split hairs. Yes we do compare apples to apples but they are just different brands of apples.
I think that here in low pressure pistol ammo we should pay close attention to the primers. When you get too hot the edge gets pretty distinctive pretty quick.
I've followed threads where they were considering ringing the barrel using the lower end loads. Most, if I remember correctly don't worry about it in a revolver because we have the space between the cylinder and the barrel where it acts like a pressure safety release blowing off overpressure quickly. But, that too is a shady grey area as this space can be a tight .003" and vary up to .032" I had in a Smith No.3., big difference there.

Primers in low pressure pistol ammo...good thought. I ended up starting with 3.6 grains and they were no problem even with that tiny grip. I will probably still put a Hogue on it for him. I could mess with the load for accuracy, but it is a snub nose with fixed sights so I will probably not do much more now that I know they shoot safely.